Motor-compressor unit for refrigerating apparatus



Dec. 20, 1938. F. L. TARLETON MOTOR-COMPRESSOR UNIT FOR REFRIGERATING APPARATUS Original Filed Oct. 51, 1934 2 Sheets-Sheet l- INVENTOR. R502 1- 72;?! Fr /v ATTORNEY.

Dec. 20, 1938. F. L. TARLETON MOTOR-COMPRESSOR UNIT FOR REFRIGERATING APPARATUS Original Filed Oct. 31, 1934 2 Sheets-Sheet 2 Patented Dec. 20, 1938 2,idi,t53

MOTOR-COMPRESSOR UNIT FOR. REFRIG- ERATING APPARATUS Frederic L. Tarleton, Dayton, Ohio, assignor to General Motors Corporation, Dayton, Ohio, a corporation of Delaware Application October 31, 1934, Serial No. 750,867 Renewed February 2, 1937 6 Claims.

use in a refrigerating system.

It is common practice in the refrigerating art to provide a motor-compressor unit "which is completely enclosed in a hermetically sealed casin within which refrigerant and lubricant for-the compressor are circulated, one of the principal advantages of thistclass of construction being that the use of a stufling box or other shaft seal is avoided. In motor-compressor units of this type, however, certain problems are incurred in connection with the maintenance of proper lubrication for the compressor which are peculiar to this type of unit since the hermetically sealed casing makes the compressor mechanism inaccessible for service and necessitates great care in insuring that all parts of the mechanism will operate properly for the life of the machine. In

refrigerators intended for household use, presentday standards also require that noise of operation of the motor-compressor unit be reduced to a value which is substantially imperceptible and it has been found that particularly with units employing a rotary-compressor, the maintenance of an unfailing supply of substantially undiluted lubricant for feed to the compressor is a major factor in insuring quiet operation.

It is an object of the present invention, therefore, to provide a motor-compressor unit preferably of the hermetically sealed type in which provision is made for insuring the maintenance of an unfailing supply of lubricant for the of the compressor.

It is a further object to provide moving parts a novel separator in-a unit of the present type for thoroughly separating the mixture of lubricant and refrigerant which is delivered from the outlet of the compressor.

Another object is to provide a compressor of this character which will be quiet throughout its useful life.

in operation construction, but which also involve of no wearing parts.

s the addition Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings. wherein a preferred form of the invention is clearly shown.

In the drawings: Fig. 1 is a vertical cross section 0 f a portion of a motor-compressor unit embodying the present invention, and shows diagrammatically the elements of a complete refrigerating system;

Fig. 2 is a fragmentary cross section on line 2-4 of Fig. 1;

Fig. 3 is a view corresponding to Fig. 1 showing a portion of the mechanism on a larger scale; and Fig. 41s a view corresponding to Fig. 1 showing a portion of the mechanism on a larger scale.

Referring now to Fig. 1, there is shown a motor- 10 compressor unit is having an outlet I! from which compressed refrigerant is delivered to a condenser 54 by a conduit iii. The condenser I, i'eed's liquefled refrigerant to a receiver HI, whence it is dellvered by conduit ifl to an expansion valve 22 15 for expanding refrigerant into an expansion coil 24. A conduit 26 delivers expanded refrigerant to the inlet 20 of the compressor iii. A thermostatic switch 30 controls the motor-compressor unit it in accordance with the temperature of 20 the expansion coil 28. The parts thus far/described constitute the conventional elements of a refrigerating system and are well known in the art.

The motor-compressor unit it] comprises a 25 housing 32 having an open bottom which is closed by a base member 34 which in turn is welded to the housing 32 at 38, to provide a hermetically sealed chamber 38. "Within the chamber 38 in the upper portion thereof, there is mounted an elec- 3o tric motor comprising a stator it and a rotor 42.

A hollow stationary shaft M is located centrally of the housing 32 and mounted rigidly, as by welding, in the base 38. A socket member s6 secured to the top of the housing 32 positions the upper 5 end of the shaft M. A hollow compressor drive shaft 48 is journaled on the shaft 44 carrying at its upper portion the rotor 52, while at the lower end, there is provided an eccentric journal 50.

Secured to the base 84 is a compressor body 40 member which may comprise a pair of bottom plates 52, a cylinder member 54, a valve cover plate 56 and a retainer plate 58. The parts 52 through it inclusive are rigidly secured together and to the base 34 and provide a cylindrical com- 5 pression chamber 50 which is concentric to the axis of the shaft 44. The cylinder member is is provided with a radial slot, not shown, for receiving a divider block in the well known manner.

Mounted within the compression chamber till is 50 a cylindrical impeller $2 which is iournaled on the eccentric journal 53 and is adapted to revolve in the compression chamber t0 without rotating. The customary divider block, not shown, is provided for dividing the chamber 50 into a compression space and a suction space. The inlet connection 28 communicates with the suction space immediately adjacent one side of the divider block, while the discharge orifice 64 communicates with the compression space immediately adjacent the other side of the divider block as is well known in the art. The discharge orifice 64 is provided with a flapper valve 66 to prevent the return of high pressure gas from the chamber 38 to the chamber 88. Communication between the chamber 38 and the outlet connection I2 is provided through the hollow shaft 44 and through one or more apertures 88 provided in the socket 48. A removable plug member In is provided in the base for charging the unit with liquid refrigerant and lubricant. Connections to the motor are brought through the base 34 by the sealed lead-in connections I2.

In order to provide for a constant supply of lubricant to the running surfaces of the compressor, the following mechanism is provided. A cover or can member 14 is attached to the compressor body member and sealed thereto at the top by a'gasket 82. The can 14 has a downwardly depending skirt 18 which embraces the compressor body member. At its top, the can member 14 is formed with an upwardly extending bulged portion 15 which terminates in a downwardly directed cylindrical sleeve 16 surrounding the shaft 48. The 'shaft 48 is made with a radius at this point at least as great as the greatest radius of the eccentric journal portion 58 in order to facilitate assembly. There is thus formed an annular chamber 84 of substantial volume on top of the compressor body for enclosing the flapper valve 66. One or more outlet ports 88 are provided in the wall of the chamber 84. For best results, it is preferred to make this outlet of a size which is several times larger than the outlet port 64 and than the clearance between shaft 48 and sleeve 18.

Secured to the valve plate 58 and the retainer plate 58 is a member 88 of peculiar shape and i which may be best described as simulating a denture or set of false teeth. The member 88 is retained in position by a pair of lugs 88 which are adapted to be received in recesses 82 and 94 formed on the retainer plate 58, and are clamped therein by the gasket 82 and the can member 14. One or more orifices 98 are formed in the upper portion of the member 88 and preferably face outwardly and upwardly from the axis of the compressor. The member 88 thus acts as a shield to keep lubricarl away from the valve 86. The members 14 and 88 may conveniently be formed of stamped sheet metal since their functions do not require greater accuracy of dimension than is readily obtainable from stamping operations.

After assembly of the unit, a charge of oil or other lubricant is placed in the chamber 38 through the plug 18 sufficient to maintain a level in the chamber 38 such as indicated by the line I88. Lubricant feed screws are provided for-insuring lubrication of the bearings associated with the shaft 48 and may comprise a downwardly directed helical groove I82 on the eccentric journal 58 and an upwardly directed helical groove I84 on the lower journal of the shaft 44. A slot I88 is formed on the central portion of the uppermost plate 52 to provide a lubricant passage from the eccentric journal 58 to the inner lower shaft bearing.

In operation, whenever current is fed to the U motor, by the closing of the switch 38, the shaft heretofore .chamber and is fed to the compression chamber 88 at a very slow rate of seepage through the running joint at the divider block. This constitutes the only direct feed of lubricant to the compression chamber 68 from the main body of lubricant in the chamber 38.

Fluid discharged through the orifice 84' is, therefore, a mixture of compressed gaseous refrigerant and lubricant, the lubricant carrying a considerable amount of refrigerant in solution. This mixture of compressed gaseous refrigerant and entrained lubricant passes through the orifices 96 into the chamber 84. Due to the comparatively large size of the chamber 84, its velocity is decreased to a very low value which gives the entrained lubricant time to precipitate before leaving the chamber 84 through the orifices 88. The precipitated lubricant collects on top of the cover plate 56 to maintain a substantial body of lubricant over the top of the compressor and on top of the upper surface of the eccentric and the impeller. Since the lubricant is in direct contact with the compressor at this point, it is brought to a high temperature by the heat of compression and substantially all of the refrigerant dissolved therein is driven out by this heat. a

Thus, it will be seen that a substantial body of practically undiluted oil is maintained above the valve plate 56 from which it flows downwardly onto the eccentric 58 and impeller 82. Thus, substantially undiluted oil is fed to the eccentric bearings and by the feed screw I82 is forced downwardly through the passage I88 to the lower shaft bearing. From this point, the feed screw I84 feeds lubricant upwardly to the upper shaft bearing, not shown. The substantially undiluted oil is also fed to the surfaces betwen the impeller 82 and the plates 56 and 52 respectively, providing lubrication and acting as a sealing fluid therefor. It has been found that considerable noise in compressors of the present type has been caused by lack of maintenance of a sufficient supply of lubricant for these surfaces, particularly at starting, which lets the lubricant film break down and permits a slight oscillating action of the impeller 82 about a horizontal axis.

The compressed gaseous refrigerant leaving the orifices 88 passes through the chamber 38 and up through the air gap of the motor and through ports in the stator or rotor (not shown) to enter the orifices 88 and pass through the hollow shaft 44. Since the orifices 88 are at the center of the unit, and since the rotor maintains the body of refrigerant revolving in the chamber 38, any entrained lubricant which is not already precipitated will be separated through centrifugal action and practically lubricant-free refrigerant will be delivered at the outlet I2.

Thus, the present invention provides for con- .tinued satisfactory operation of a hermetically sealed motor-compressor unit throughout subtion thereof by maintaining a supply of concentrated substantially undiluted lubricant for feeding to all the working surfaces of the compressor.

While the form of embodiment of the invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. In a motor-compressor unit the combination of a hermetically sealed housing, a motor in the upper portion of the housing, a rotary compressor in the lower portion of the housing, a central vertical drive shaft connecting the motor and compressor, an outlet for compressed fluid in the top of the compressor, a flapper valve controlling said outlet, means secured to the top of the compressor and surrounding said shaft defining a chamber enclosing said outlet and sufficiently large to reduce the velocity of fluid flow through said chamber enough to permit the lubricant entrained in the fluid to precipitate in the chamber, an outlet "for compressed fluid at the top of said chamber which opens into said housing and is spaced from the compressor outlet and substantially larger than the compressor outlet and the area between the shaft and said means, a passage for conveying precipitated lubricant from said chamber to the compressor, and means in said chamber for shielding the flapper valve from the precipitated lubricant.

' pressed fluid in the top of said cylinder, a flapper valve controlling said outlet, means secured to said cylinder and surrounding said shaft defining a chamber enclosing said outlet and sufficiently large to reduce the velocity of fluid flow through said chamber enough to permit the lubricant entrained in the fluid to precipitate in the chamber, an outlet for compressed fluid at the top of said chamber which opens into said housing and is spaced from the compressor outlet and substantially larger than the compressor outlet and the area between said shaft and said means, a passage for conveying precipitated lubricant from said chamber to the cylinder, and means in said cham-' her for shielding the flapper valve from precipitated lubricant.

3. In a compressor, a sealed housing, avertical cylinder in said housing," a vertical drive shaft in said housing, a rotary piston in said cylinder actuated by said drive shaft, an outlet for compressed fluid in the top of said cylinder, a flapper valve controlling said outlet, means secured to said cylinder and surrounding said shaft defining a chamber enclosing said outlet and sufficiently large to reduce the velocity of fluid flow through said chamber enough to permit the lubricant entrained in the fluid to precipitate in the chamber,

- an outlet for compressed fluid at the top of said chamber-which opens into said housing and is spaced from the compressor outlet and substantially larger than the compressor outlet and the area between said shaft and said means, a passage for conveying precipitated lubricant from said chamber to the cylinder, and means in said chamber for shielding the flapper valve from precipitated lubricant, said last named means including an inverted metallic cup over said valve with an opening at the top.

4. In a motor-compressor unit, the combination of a hermetically sealed housing containing a supply of lubricant, a rotary compressor in the housing having a discharge outlet at the upper side thereof and a divider block slidably mounted in the side wall thereof, a flapper valve at said discharge outlet, a rotary member projecting upwardly from said compressor, and a sheet metal cover member sealed to the upper side of said compressor, said cover member having a skirt which embraces the compressor and which terminates below the lubricant level whereby leakage around the divider block causes lubricant to be drawn up between the skirt and the compressor and into the compressor, the upper part of said cover member having another skirt portion above the compressor extending a substantial distance downwardly along said rotary member and closely surrounding the rotary member throughout said distance. and defining with another portion of said cover member a lubricant precipitating chamber substantially enclosing said discharge outlet.

5. In combination'with a compressor having a discharge outlet through which a mixture of compressed gas and lubricant is discharged, a rotary shaft projecting from one side thereof, a stamped sheet metal member embracing a portion of said compressor and forming a lubricant precipitating chamber over said discharge outlet, said metal member having an aperture provided with a cylindrical sleeve through which said shaft extends, said sleeve extending a substantial distance along said shaft and being slightly larger than said shaft so as to permit the escape of gas between said sleeve and said shaft, and a stamped sheet metal member in said chamber for shielding said discharge outlet, said last-named metal member comprising an inverted cup placed over said discharge outlet with provisions for the escape of fluid through which the discharge from said compressor outlet is caused to flow during operation of the compressor. v v

6. In a compressor, a sealed housing, a cylinder in said housing, a drive shaft in said housing, a piston in said cylinder actuated by said drive shaft, said cylinder having an outlet for compressed fluid, a valve controlling said outlet, a sheet metal stamping means secured to said cylinder and surrounding said shaft defining a chamber enclosing saidoutlet and sufficiently large to reduce the velocity of fluid flow through said chamber enough to permit the lubricant entrained in the fluid to precipitate in the chamber, said chamber having an outlet for compressed fluid which opens into said housing and is spaced from the compressor outlet and substantially larger than the compressor outlet and the area between said shaft and said means, a passage for conveying precipitated lubricant from said chamber to the cylinder, and means in said chamber for shielding the valve from precipitated lubricant.

FREDERIC L. TABLE-TON. 

